search for: ldwrdptr

...from memory address P is to be expaneded to ld r1, P+ ld r2, P where "ld _, P+" is an instruction that loads a single byte from P, and post-increments P by one. How can I represent this behaviour in LLVM? Currently, I have let Constraints = "@earlyclobber $reg" in def LDWRdPtr : Pseudo<(outs DREGS:$reg), (ins PTRREGS:$ptrreg), "ldw\t$reg, $ptrreg", [(set i16:$reg, (load i16:$ptrreg))]>, Requires<[HasSRAM]>; The problem, of course, is that with this definiti...

Hi, During instruction selection, I have the following code for certain LOAD instructions: const LoadSDNode *LD = cast<LoadSDNode>(N); SDNode* LDW = CurDAG->getMachineNode(AVR::LDWRdPtr, SDLoc(N), VT, PtrVT, MVT::Other, LD->getBasePtr(), LD->getChain()); // Honestly, I have no idea what this does, but other memory // accessing instructions have something similar... MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1); Me...

On Sun, 28 May 2017, David Chisnall wrote: >> let Constraints = "@earlyclobber $reg" in >> def LDWRdPtr : Pseudo<(outs DREGS:$reg), >> (ins PTRREGS:$ptrreg), >> "ldw\t$reg, $ptrreg", >> [(set i16:$reg, (load i16:$ptrreg))]>, >> Requires<[HasSRAM]>; >> >> The p...

Thanks. I saw the header comments but it wasn’t clear to me what the difference between those concepts is? My slightly vague understanding is IsDef means that the register specified by this operand is set by the machine instruction. So I understand that to mean the MO will override that register? Also things like early clobber, perhaps there is another document that clarifies some of these

On 7/29/2017 1:28 AM, Dr. ERDI Gergo via llvm-dev wrote: > Hi, > > During instruction selection, I have the following code for certain > LOAD instructions: > > const LoadSDNode *LD = cast<LoadSDNode>(N); > SDNode* LDW = CurDAG->getMachineNode(AVR::LDWRdPtr, SDLoc(N), > VT, PtrVT, MVT::Other, > LD->getBasePtr(), LD->getChain()); > > // Honestly, I have no idea what this does, but other memory > // accessing instructions have something similar... > MachineSDNode::mmo_iterator MemOp = MF->allocateM...

The reason the ones in PPCInstrInfo.td don't have the patterns to match is the reason they are more analogous to your problem. Namely, tblgen does not have a way to produce nodes with more than one result. The load-with-update instructions do exactly that - one of the inputs is also an output, but the other output is independent (and necessarily a separate register). The FMA variants have

On Tue, 30 May 2017, Nemanja Ivanovic wrote: > This is typically accomplished with something like PPC's `RegConstraint` and > `NoEncode`. You can see examples of it that are very similar to what you're after in > PPC's load/store with update forms (i.e. load a value and update the base register > with the effective address - these are used for pre-increment loads/stores).